Inside Sonnet Technologies' Echo Express Pro
Sonnet Technologies actually sells three different Thunderbolt-based expansion chassis for PCI Express cards, differentiated mostly by size.
The largest Echo Express Pro, which we have here in the lab, takes two full-length cards (or, a single double-slot card). That's an $800 dollar proposition. The vanilla Echo Express supports a single PCIe card with a maximum length of 7.75". It sells for $600. Finally, the entry-level Echo Express SE also supports a single-slot PCIe device, but it's only large enough for a half-length board. A $400 price tag makes it more affordable, though.
To be clear, Sonnet Technologies doesn't really position these enclosures as solutions for adding discrete graphics to consumer-level notebooks. Given their price points, they're much better suited to workstation-oriented applications: adding the expandability of an eight-port RAID controller, tacking on professional A/V editing cards, or even incorporating 8 Gb Fibre connectivity to a mobile machine.
| Comparison | PCIe Slots | Maximum Card Length | Maximum Card Height | Maximum Card Width | Power Supply |
|---|---|---|---|---|---|
| Echo Express Pro | 2 x16 | 12.28" (Full) | 6.6" (Full) | 2 Single-Width1 Double-Width | 150 W |
| Echo Express | 1 x16 | 7.75" | 6.6" (Full) | 1 Double-Width | 100 W |
| Echo Express SE | 1 x16 | 6.6" (Half) | 6.6" (Full) | 1 Single-Width | 60 W |
The Echo Expresses feature a simple and elegant external design. Their solid aluminum frames serve two purposes: aesthetically, they match the silver shell of Apple's Mac computers, and functionally, they help dissipate heat from the add-in card inside. In an effort to further address thermal concerns, Sonnet Technologies employs fans on the front and back of the enclosures to help maintain adequate airflow.
Installing a card is straightforward. Slide off the top cover after removing the rear security screw, and then drop in your PCI Express-based board. Just be aware that Sonnet doesn't provide any additional power connectors, which may limit what you're able to install. The enclosures employ a proprietary power circuit, so you can't simply upgrade the power supply.
There are also implications for adding a storage device with SATA/SCSI support via Thunderbolt. Neither the Echo Express Pro nor the Echo Express are designed to support internal storage devices. The correct way to use the product would be to install a controller with external connectivity, and then attach a JBOD designed to house and power a number of disk drives.
All three enclosures expose 16-lane connectors, accommodating anything from high-end graphics cards to dinky little sound cards. Because Thunderbolt is limited to 10 Gb/s of throughput, though, you can really only expect the equivalent of a four-lane second-gen link. As a result, bandwidth-constrained workloads will suffer compared to dropping a card with a x16 connector into a motherboard's native x16 slot.